you have to cut the guides/spring seat down for doubles in order to locate the inner spring.
Check for what seals the guides are setup for, and also retainer to guide clearance at the lift you are running, you can do a mock up with
cam/1lifter/pushrod/1 rocker + shaft/ 1 valve w/lite checking spring and then measure at the retainer.
But just having the theoretical 500/496 lift clearance between retainer/guide should be fine.